A 3D modulated speckle pattern is stored in terms of the refractive index variation in a photorefractive BTO crystal. An image of a random diffuser is formed onto the crystal by means of a lens, which has a mask with two apertures. The intensity distribution received by the crystal creates a space charge field that indices through the linear electro- optic effect, a spatial variation of the refractive index. The angular selectivity involved in the volume nature of the registered speckle and its main features are analyzed. Besides, applications to optical processing are presented.